1. Field of the Invention
The invention relates to a winding machine for winding a web of paper or other raw material or textile stocks, e.g. polymeric films, into large rolls. More particularly, it relates to a dual-drum winding machine capable of producing uniformly tightly wound rolls of such web material across the entire radius of the roll.
2. Description of the Related Art
In conventional dual-drum winding machines, a web of material, e.g. paper, polymeric sheet or film, textile material, etc., is continuously wound on a central core from a source of the web material that is fed continuously from outside the winding machine. As more of the web material becomes wound around the central core, the diameter of the resulting roll increases commensurately, with the increasing diameter roll being supported in a position substantially centered between two adjacent and level support rolls or drums.
U.S. Pat. No. 5,593,106 discloses a typical conventional dual-drum winder characteristic of the prior art, and is incorporated herein by reference. FIG. 1 of the '106 patent shows the web roll of increasing diameter supported in a rolling position B between two adjacent and level winding drums 36 and 38. As the drums 36 and 38 are rotated clockwise, the web roll is thereby caused to rotate counterclockwise and thus to wind additional web material thereon from the web material source shown at W in FIG. 1 of '106. Once the web roll has achieved its final diameter D, the piston-driven cutter 48 extends upward to cut the web source from the now complete web roll, and the finished roll is urged out of the machine via an ejection mechanism comprising a sweep arm 42 and associated piston 44 as shown in the figure.
From FIG. 1 of '106 and the foregoing description, it will be evident to those skilled in the art that existing winding machines such as that disclosed in '106 rely on the web source, which supplies the web material to the winding machine, to also supply the necessary web tension to provide a tightly wound finished web roll. This arrangement results in poorly tensioned web rolls causing the finished rolls to have nonuniform radial or layer density (density of web material on the finished roll measured in layers of web material per radial inch).
In addition, as the source web material is severed from the finished web roll, a long and loose untensioned flap portion of source web material results. This loose flap portion is pressed against a newly supplied central core to begin forming the next successive web roll. The loose flap portion is not tensioned by the web source because the web is severed downstream of the leading drum roller (e.g. roller 32 in FIG. 1 of '106). Hence, the loose flap portion of the web material typically includes myriad folds, creases, lines, wrinkles and other random undesirable gatherings of web material characteristic of untensioned webs. As this loose flap portion is laid against the spinning newly supplied central core, additional layers of web material are wound thereover as the web roll grows. As these additional layers are wound on the creased, untensioned underlying layers, they too become creased and folded, exhibiting undesirable gathering characteristic of web material that has not been properly tensioned. The fact that the web is conventionally severed some distance (e.g. 12 inches, or up to 2 or 4 feet or more) from the newly supplied central core contributes significantly to this problem because the resulting loose flap is very long; sometimes many times the circumference of the central core. The overall result is that a significant portion of the finished web roll within a certain radial distance from the central core is unusable in subsequent processing operations for which tightly and uniformly tensioned material webs are required. In fact, the folds and creases in the rolled web material can lead or contribute to exactly the edge profile defects of finished web rolls with which the '106 patent was principally concerned.
Accordingly, there is a need in the art for a dual-drum winding machine that overcomes the aforementioned deficiencies characteristic of the prior art. Preferably, such an improved dual-drum winding machine will not rely solely on the web source to supply web tension to the forming web roll. Also preferably, such an improved machine will significantly minimize or substantially eliminate the loose flap portion supplied to fresh central cores which has been characteristic of and problematic in the prior art.